In a central dictation recording system, a record-playback machine may record messages dictated from several remote stations by several different individuals. Privacy of dictated messages if of prime consideration so that after a message is recorded on the central dictation record-playback machine, it is important to ensure that the next individual dictating a message on the same machine is not able to backspace into the previously recorded messages. It is also important to preclude such backspacing because the accidental backspacing into a previously recorded message and then the beginning of the recording of a new message can result in the erasure of the portion of the previously recorded message into which the backspacing occurred.
Backspacing into previously recorded messages may be prevented by methods such as providing a tone burst at the end of the dictated message where the backspacing means is precluded from backspacing the recording tape beyond the tone burst location on the recording tape. Other methods may involve mechanisms which prevent backspacing into pre-recorded messages, however, such mechanisms are usually very complicated in structure and quite costly.
It is therefore an object of the invention to provide an efficient mechanically activated anti-reverse means which precludes backspacing into previously recorded messages on a central dictation recording system.
It is another object of the invention to provide an anti-reverse means which is adapted for use on a central dictation recording machine which has a record medium index which is adapted to return to its start position when dictation of a message from a remote station is completed.
It is a further object of the invention to provide an anti-reverse means which is controlled from a remote station such as a telephone.
It is yet another object of the invention to provide a simple electrical circuit which is used in conjunction with the PBX system of the Bell Telephone to control the anti-reverse means.
It is another object of the invention to provide a normally open switch which controls the backspacing means which when contacted by the record medium index as it returns to its start position, closes the switch until the record medium index has moved far enough away from its start position during subsequent recording of the message that backspacing is only permitted to the beginning of the message being presently recorded.